Typical moving coil assembly 100 actuators utilise radial magnets in the field structure, or axial central magnets. A typical “loudspeaker” design uses an annular axial magnet. Production of a large payload acceleration with little electrical power requires a large radial magnetic flux. To increase the magnetic flux of such designs requires that the external dimensions of the actuator be increased. This may not be an option as the space required for an increased-size actuator may not be available, so generally a compromise or work-around has to be found.
The described embodiments seek to mitigate the problems associated with the known designs described above.